In recent years increased attention has been directed toward both decreased noise pollution and energy conservation in buildings and homes. Numerous studies have shown that principal offenders in unwanted sound transmission and energy loss in buildings and homes are the window areas.
Improved insulation in walls and ceilings has made measurable improvements in the sound and energy integrity of existing and new construction leaving the window areas as the places requiring major redesign in order to meet acceptable standards. A first major step was taken when single glazing is replaced by dual glazing with an air space between the two window lites. The air space and the second lite will typically reduce the sound transmission through a typical residential window and the thermal energy by significant amounts resulting in widespread adoption of dual glazing.
It has more recently been recognized that a major source of loss of energy through a typical horizontal sliding window even using dual glazing is via air infiltration through the window around the movable sash. The common approach to the minimization of air infiltration has been to install pile fabric type seals similar to the type long used for auto window sealing. In autos such seals have met existing needs and such seals have been considered acceptable in building window installations.
For many years, a window which under test conditions passed less than 0.75 cubic foot of air per minute with a standard pressure differential was considered satisfactory. More recently, standards of 0.50 and 0.37 cubic foot per minute of air infiltration have been established by such organizations as the Aluminum Architectural Manufacturer's Association.
Also, the sound transmission class (STC rating) of a window is important, particularly in noisy locations. Heretofore a rating of 30 could only be achieved using dual glazing. However, I have determined that it is possible to match that standard using only single glazing, or exceed that standard with dual glazing, provided the improved panel mounting and sealing features which I have developed are used.